In 1970, Massachusetts General Hospital (MGH) researchers in the Physics Research Laboratory, under Dr. Gordon Brownell, utilized 2D arrays of NaI crystals to create the “Positron Camera I” (PC-I), designed in 1968 and active around 1969–1970, which produced early tomograms.

Dr. Brownell and neurosurgeon William Sweet pioneered the use of positron-emitting tracers for medical imaging in the early 1950s at MGH.

MGH work was instrumental in developing detector technology and tracer applications that transitioned PET from a concept to a practical imaging tool.